/**
 * This file is part of 1genia trampoline
 * Copyright (C) 2007 1genia (contact@1genia.com)
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; version 3 of the License. 
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details. 
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; see the file COPYING.TXT.  If not,
 * write to the Free Software Foundation, Inc., 51 Franklin Street,
 * Fifth Floor, Boston, MA 02110-1301, USA. 
 **/
package com.genia.toolbox.basics.bean.impl;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;

import com.genia.toolbox.basics.bean.InputStreamFactory;
import com.genia.toolbox.basics.exception.technical.TechnicalFileNotFoundException;

/**
 * An {@link InputStreamFactory} that generate {@link InputStream} from a byte
 * array and a {@link File}.
 */
public class CacheInputStreamFactory
    implements InputStreamFactory
{
  /**
   * the buffer containing the first datas.
   */
  private final transient byte[] buffer;

  /**
   * the {@link File} containing the remaining datas.
   */
  private final transient File file;



  /**
   * constructor.
   * 
   * @param buffer
   *          the buffer containing the first datas
   * @param file
   *          the {@link File} containing the remaining datas
   */
  public CacheInputStreamFactory(byte[] buffer, File file)
  {
    this.buffer = buffer;
    this.file = file;
  }



  /**
   * Called by the garbage collector on an object when garbage collection
   * determines that there are no more references to the object. A subclass
   * overrides the <code>finalize</code> method to dispose of system resources
   * or to perform other cleanup.
   * <p>
   * It allows to clean the {@link File}.
   * 
   * @throws Throwable
   *           if an error occured
   */
  @Override
  public void finalize()
      throws Throwable
  {
    try {
      if (file != null) {
        file.delete();
      }
    }
    finally {
      super.finalize();
    }
  }



  /**
   * the factory method.
   * 
   * @return an {@link InputStream}
   * @throws TechnicalFileNotFoundException
   *           when an error occured
   * @see com.genia.toolbox.basics.bean.InputStreamFactory#getInputStream()
   */
  public InputStream getInputStream()
      throws TechnicalFileNotFoundException
  {
    try {
      return new MergedInputStream(new ByteArrayInputStream(buffer), new FileInputStream(file));
    }
    catch (FileNotFoundException e) {
      throw new TechnicalFileNotFoundException(e);
    }
  }
}
